MPlayerControlAPI Class Reference

API for controlling mplayer process. More...

#include <MPlayerControlAPI.h>

List of all members.

Public Slots
void	NewDataInStdout ()
	Receive messages printed out by mplayer.
void	playingProgressTimerTimedOut ()
	Called when iPlayingProgressTimer times out.
Signals
void	startPlayingProgressTimer ()
	Internal signal. Emitted to start iPlayingProgressTimer.
void	stopPlayingProgressTimer ()
	Internal signal. Emitted to stop iPlayingProgressTimer.
void	log (const QString &msg)
	Can be used to get log about what is happening in here.
void	finishedPlaying ()
	Emitted when mplayer finishes playing a file. Doesn't get emitted however if the playing gets stopped by calling Stop().
void	playingProgress (quint64 value)
	Emitted when NewDataInStdout() receives information about the progress of the file currently being played from mplayer.
void	gotLength (qreal length)
	Emitted when NewDataInStdout() receives the total length of file from mplayer.
void	gotAspectRatio (qreal aspectRatio)
	Emitted when video aspect ratio is determined by calculation from width and height or reported by mplayer.
void	gotMediaTitle (const QString &title)
	Emitted when NewDataInStdout() receives title of file from mplayer.
void	gotMediaArtist (const QString &artist)
	Emitted when NewDataInStdout() receives artist of file from mplayer.
void	gotMediaCreationDate (const QString &creationDate)
	Emitted when NewDataInStdout() receives creation date of file from mplayer.
void	gotMediaAlbum (const QString &album)
	Emitted when NewDataInStdout() receives album from which the file is from from mplayer.
void	gotMediaFilename (const QString &fileName)
	Emitted when NewDataInStdout() receives filename from mplayer.
Public Member Functions
void	SetWindowID (WId graphicArea)
	Redirect video output to own window/widget.
void	SetFile (const QString &fileName)
	Set name of the file that should be played next.
QString	GetFile ()
	Get name of the file that is set to be played next.
int	Play ()
	Start playing.
int	Pause ()
	Pause or resume playing from pause.
int	TogglePlayPause ()
	Pause or resume playing from pause or start playing.
bool	Stop ()
	Stop playing.
void	SetVolume (int vol)
	Set the volume.
void	Seek (int pos)
	Seek from currently played file.
bool	isPlaying ()
	Check if mplayer is currently playing something.
QString	getMplayerVersion ()
	Get the version of mplayer.
int	initMplayerProcess ()
	Start process for mplayer.
Private Attributes
bool	iHasVideoWidth
	Track wether we have any information about possible width of video currently being played.
bool	iHasVideoHeight
	Track wether we have any information about possible height of video currently being played.
qreal	iVideoWidth
	Stores the width of video currently being played.
qreal	iVideoHeight
	Stores the height of video currently being played.
QString	iFileName
	Stores the name of file that is set to be played next by SetFile(const QString &fileName).
QString	iMplayerVersion
	Stores the version of mplayer.
bool	iIsPlaying
	True if we are playing something or paused, else false.
WId	iMplayerVideoOutputWindowId
	ID of the window to which mplayer should redirect it's video output.
QProcess *	iMplayerProcess
	mplayers process.
bool	iPaused
	true if paused, else false.
int	iVolume
	Stores the current volume setting.
QTimer	iPlayingProgressTimer
	Timer used for querying playing progress from mplayer with certain intervall.
QSemaphore *	iPlayingProgressSem
	Semaphore for preventing us to query playing progress faster than we get responses from mplayer.

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Detailed Description

API for controlling mplayer process.

Introduces functions for doing following things with mplayer.

• Play a file
• Stop playing
• Pause/resume playing
• Set volume
• Seek
• Redirect video output to own window/widget
• Get things like Artist, title, year, album from ID tags
• Track the progress of playing.

  Note:

  You must call initMplayerProcess() before you can start playing anything.

  Normal way to start playing a file with this api is:
• Create object
• Call initMplayerProcess()
• Call SetFile(const QString &fileName) to set the file to be played
• Call Play() to start playing.

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Member Function Documentation

QString MPlayerControlAPI::GetFile

(

)

Get name of the file that is set to be played next.

The function will return the name of the file that is set to be played next.

Returns:

name of the file that is set to be played when Play() is called.

QString MPlayerControlAPI::getMplayerVersion

(

)

Get the version of mplayer.

Returns:

String containing the version of mplayer.

void MPlayerControlAPI::gotAspectRatio

(

qreal

aspectRatio

)

[signal]

Emitted when video aspect ratio is determined by calculation from width and height or reported by mplayer.

Parameters:

aspectRatio

Aspect ratio of video.

void MPlayerControlAPI::gotLength

(

qreal

length

)

[signal]

Emitted when NewDataInStdout() receives the total length of file from mplayer.

Parameters:

length

Length of file in seconds.

void MPlayerControlAPI::gotMediaAlbum

(

const QString &

album

)

[signal]

Emitted when NewDataInStdout() receives album from which the file is from from mplayer.

Parameters:

album

Name of the album this is from.

void MPlayerControlAPI::gotMediaArtist

(

const QString &

artist

)

[signal]

Emitted when NewDataInStdout() receives artist of file from mplayer.

Parameters:

artist

Performing artist's name.

void MPlayerControlAPI::gotMediaCreationDate

(

const QString &

creationDate

)

[signal]

Emitted when NewDataInStdout() receives creation date of file from mplayer.

Parameters:

creationDate

Creation date of the file.

void MPlayerControlAPI::gotMediaFilename

(

const QString &

fileName

)

[signal]

Emitted when NewDataInStdout() receives filename from mplayer.

Parameters:

fileName

Name of the file that is currently being played withouth complete path.

void MPlayerControlAPI::gotMediaTitle

(

const QString &

title

)

[signal]

Emitted when NewDataInStdout() receives title of file from mplayer.

Parameters:

title

Title of the file (such as song name).

int MPlayerControlAPI::initMplayerProcess

(

)

Start process for mplayer.

This function must be succesfully called before this API can be used for playing anything.

Returns:

_MPLAYER_START_ERROR_FAILED_TO_START if mplayer process couldn't be started for some reason.

_MPLAYER_START_SUCCESS on success.

bool MPlayerControlAPI::isPlaying

(

)

Check if mplayer is currently playing something.

Returns:

true if mplayer is playing (or paused), false if mplayer is stopped.

void MPlayerControlAPI::NewDataInStdout

(

)

[slot]

Receive messages printed out by mplayer.

This slot receives messages printed out by mplayer and parses any interesting information from them. Following things are captured from mplayer's output.

• Mplayers version.
• Length of file that started playing. Reported out with signal gotLength().
• Possible aspect ratio of video. Reported out with signal gotAspectRatio(qreal aspectRatio).
• Possible width of video.
• Possible height of video.
• Name of the file that started playing. Reported out with signal gotMediaFilename(const QString &fileName).
• Current position in file. Reported out with signal playingProgress(quint64 value).
• Error message stating that the current position in file could not be retrieved. This is used for determining when we have finished playing current file. Emits signal finishedPlaying().

In addition the following things are taken from possible ID tags in files.

• Title of the file (song title). Reported out with signal gotMediaTitle(const QString &title).
• Artist. Reported out with signal gotMediaArtist(const QString &artist).
• Creation date (year field in ID3V1). Reported out with signal gotMediaCreationDate(const QString &creationDate).
• Album. Reported out with signal gotMediaAlbum(const QString &album).

int MPlayerControlAPI::Pause

(

)

Pause or resume playing from pause.

Can be used to pause or resume playing from pause. Doesn't resume playing if playing is stopped.

Returns:

allways 0 (TODO errors...)

int MPlayerControlAPI::Play

(

)

Start playing.

Returns:

_MPLAYER_START_ERROR_ALLREADY_PLAYING if mplayer is allready playing something.

_MPLAYER_START_ERROR_NOTHING_TO_PLAY if nothing has been set to be played. SetFile(const QString &fileName) must be called before calling Play()

void MPlayerControlAPI::playingProgress

(

quint64

value

)

[signal]

Emitted when NewDataInStdout() receives information about the progress of the file currently being played from mplayer.

Parameters:

value

Location in file measured as 0.1 seconds.

void MPlayerControlAPI::playingProgressTimerTimedOut

(

)

[slot]

Called when iPlayingProgressTimer times out.

Tests first if iIsPlaying is true. If not, then nothing is done. If is then will test iPlayingProgressSem and if the value is greater than 0, will send query to mplayer about playing progress, decrease the value of the semaphore by one and restart iPlayingProgressTimer.

void MPlayerControlAPI::Seek

(

int

pos

)

Seek from currently played file.

Parameters:

pos

a number between 0 and maximum value passed by signal void gotLength(qreal length)

void MPlayerControlAPI::SetFile

(

const QString &

fileName

)

Set name of the file that should be played next.

Parameters:

fileName

String holding the filename

The function will set the name of the file that should be played next. This function does not start playing the file. To start playing you must call Play() after setting filename.

void MPlayerControlAPI::SetVolume

(

int

vol

)

Set the volume.

Parameters:

vol

a number from 0 to 100. 0 means silent, 100 means full volume.

void MPlayerControlAPI::SetWindowID

(

WId

graphicArea

)

Redirect video output to own window/widget.

Parameters:

graphicArea

Window ID of the widget that mplayer should use as video output.

bool MPlayerControlAPI::Stop

(

)

Stop playing.

Returns:

false if mplayer was allready stopped, else true.

int MPlayerControlAPI::TogglePlayPause

(

)

Pause or resume playing from pause or start playing.

Function is written for convenience to combine Pause() and Play() and does the wollowing:

• If mplayer is playing something, will pause the playing.
• If mplayer is paused, will resume playing.
• If mplayer isn't playing anything, will attempt to start playing by calling Play().

Returns:

_MPLAYER_START_SUCCESS If paused or resumed from pause.

error code returned by Play() if attempted to start playing.

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Member Data Documentation

MPlayerControlAPI::iHasVideoHeight [private]

Track wether we have any information about possible height of video currently being played.

Reset by Play() when changing file. Set by NewDataInStdout() when it receives height of video.

MPlayerControlAPI::iHasVideoWidth [private]

Track wether we have any information about possible width of video currently being played.

Reset by Play() when changing file. Set by NewDataInStdout() when it receives width of video.

MPlayerControlAPI::iMplayerVersion [private]

Stores the version of mplayer.

The string contains information about mplayer shortly after calling initMplayerProcess(). The time between calling initMplayerProcess() and information getting stored to this string depends on how fast mplayer process starts and reports it's version via stdout ( NewDataInStdout() ). Call QString getMplayerVersion() to query for this information.

MPlayerControlAPI::iPlayingProgressSem [private]

Semaphore for preventing us to query playing progress faster than we get responses from mplayer.

This semaphore is first tested by playingProgressTimerTimedOut() and if the value is greater than 0, playingProgressTimerTimedOut() will send query to mplayer about playing progress and decrease the value of the semaphore by one. When NewDataInStdout() receives response to this query (that can be either playing progress or error stating that it couldn't be read) it will increase the value of this semaphore by one allowing more queries to be sent.

MPlayerControlAPI::iVideoHeight [private]

Stores the height of video currently being played.

Once both height and width have been received from mplayer process (MPlayerControlAPI::iHasVideoWidth and MPlayerControlAPI::iHasVideoHeight are both true) iVideoWidth and iVideoHeight are used to calculate and report the aspect ratio of the video being played. The aspect ratio is allso queried separately but it is sometimes reported as 0 by mplayer.

MPlayerControlAPI::iVideoWidth [private]

Stores the width of video currently being played.

Once both height and width have been received from mplayer process (MPlayerControlAPI::iHasVideoWidth and MPlayerControlAPI::iHasVideoHeight are both true) iVideoWidth and iVideoHeight are used to calculate and report the aspect ratio of the video being played. The aspect ratio is allso queried separately but it is sometimes reported as 0 by mplayer.

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The documentation for this class was generated from the following files:

• xiaoningsdiary/include/MediaPlayer/MPlayerControlAPI.h
• xiaoningsdiary/moc_MPlayerControlAPI.cpp
• xiaoningsdiary/source/MediaPlayer/MPlayerControlAPI.cpp